Upper gastrointestinal training in the UK and Ireland: a Roux Group Study.

INTRODUCTION: Surgical training programmes in the United Kingdom and Ireland (UK&I) are in a state of flux. This study aims to report the contemporary opinions of trainee and consultant surgeons on the current upper gastrointestinal (UGI) training model in the UK&I. METHODS: A questionnaire was developed and distributed via national UGI societies. Questions pertained to demographics, current training evaluation, perceived requirements and availability. RESULTS: A total of 241 responses were received with representation from all UK&I postgraduate training regions. The biggest discrepancies between rotation demand and national availability related to advanced/therapeutic endoscopy and robotic surgery, with 91.7% of respondents stating they would welcome greater geographical flexibility in training. The median suggested academic targets were 3-5 publications (trainee vs consultant <3 vs 3-5, p<0.001); <3 presentations (<3 vs 3-5, p=0.002); and 3-5 audits/quality improvement projects (<3 vs 3-5, p<0.001). Current operative requirements were considered achievable (87.6%) but inadequate for day one consultant practice (74.7%). Reassuringly, 76.3% deemed there was role for on-the-job operative training following consultant appointment. Proficiency in diagnostic endoscopy was considered a minimum requirement for Certificate of Completion of Training (CCT) yet the majority regarded therapeutic endoscopy competency as non-essential. The median numbers of index UGI operations suggested were comparable with the current curriculum requirements. Post-CCT fellowships were not considered necessary; however, the majority (73.6%) recognised their advantage. CONCLUSIONS: Current CCT requirements are largely consistent with the opinions of the UGI community. Areas for improvement include flexibility in geographical working and increasing national provisions for high-quality endoscopy training.

Sprayed cultured autologous keratinocytes in the treatment of severe burns: a retrospective matched cohort study.

The standard treatment of burns is early excision followed by autologous skin grafting. The closure of extensive deep burns poses a considerable challenge. Cultured autologous keratinocytes have been used since 1981 in an effort to improve healing. However, the time required to culture the cells and the lack of a dermal component limit the expectations of outcome. Our aim was to compare the duration of hospital stay between patients who were treated with autologous skin grafts and cultured autologous keratinocytes and those who were treated with autologous skin grafting without cultured autologous keratinocytes. In this retrospective study all patients treated with cultured autologous keratinocytes between 2012 and 2015 were matched by size and depth of burn with patients not treated with cultured autologous keratinocytes. Multivariable regression was used to analyse associations between duration of hospital stay and treatment adjusted for age, mortality, size and depth of the burn. Then, we investigated the possibility of differentiation of human bone marrow stem cell line to keratinocyte- like cells as a future direction. The regression analysis showed a coefficient of 17.36 (95% CI -17.69 to 52.40), p= 0.32, for hospital stay in the treatment group, compared with the matched group. Our results showed no difference in the duration of hospital stay between the two treatments. Autologous stem cells should be considered as a future modality of burn management, although further studies are needed.

Le traitement de référence des brûlures est l'excision- greffe précoce, qui est problématique en cas d'atteinte étendue. La culture de kératinocytes autologues est utilisée depuis 1981 dans le but de répondre à cette problématique mais se heure au temps nécessaire à sa mise en oeuvre, ainsi qu'à l'absence de feuillet dermique, génératrice de séquelles. Cette étude a comparé la durée de séjour des patients traité par excision- greffe et culture de kératinocytes à celle des patients traités de manière conventionnelle. Les patients hospitalisés entre 2012 et 2015 ont été comparés à des patients de même surface et profondeur traités conventionnellement, en utilisant une analyse multivariée ajustée sur l'âge, la mortalité, la surface et la profondeur de la brûlure. L'analyse n'est pas significative (coefficient 17,36 ; IC95 -17,69 à 52,4 ; p= 0,32). Il serait utile d'étudier l'utilisation des cellules souches médullaires, différentiées en kératinocytes, dans un protocole de culture.

Conductometric determination of trospium chloride by silver nitrate and phosphomolybidic acid.

Two simple, accurate, sensitive and precise conductometric methods were developed for determination of trospium chloride in pure form and in pharmaceutical formulations. It is based on using two precipitating reagents; Phosphomolybdic acid (PMA) and Silver nitrate (AgNO3). The mean recovery for Silver nitrate is in the range (98-100.95%) and for Phosphomolybdic acid in the range (98-101.69%). A molar ratio has been determined conductometrically for the two reagents, revealed (1/1) for (drug/reagent). The proposed methods were validated and successfully applied for the determination of the studied drug in pure form and in its pharmaceutical preparation. The results of the proposed methods were compared to the results of reported method with no significant difference between them.

Micellar high performance liquid chromatographic method for separation and validation of two anti-hepatitis C- virus drugs in pure form, human plasma and human urine.

OBJECTIVES: In the present study, an eco- friendly micellar liquid chromatographic technique was validated for separation and quantification of two drugs; namely ribavirin (RIV), and sofosbuvir (SBV) in pure form, pharmaceuticals containing them, human plasma and human urine. These drugs are administered co-administered for treatment of Hepatitis C virus (HCV) that causes hepatitis C in humans. MATERIAL AND METHODS: These drugs were separated using Nucleosil 100-5 phenyl column. Sodium dodecyl sulphate (SDS) solution (0.05M, pH 7.0) containing triethylamine (0.3%) and n-butanol (10%) was used as a mobile phase with 1.2 mLmin-1 flow rate and 215nm detection wavelength. Nine minutes were required for resolving the two drugs from the matrix. RESULTS: The method showed good linearity for RIV and SBV with correlation coefficients (r2) more than 0.9996 within the concentration ranges of (20-400) and (40-400) ngmL-1 in pure form, (30-300) and (50-300) ngmL-1 in human plasma and (20-400) and (40-400) ngmL-1 in human urine, respectively. CONCLUSION: The recommended method was applied for examination of RIV and SBV in pure and pharmaceuticals. The obtained results were statistically matched with reported methods with no significant differences. Also, the recommended method was effectively applied for estimation of both drugs in spiked human urine and plasma without purification or extraction steps and real samples of plasma and urine of humans having therapy of RIV and SBV, as well as, performing tablets dissolution-rate tests with satisfactory results.

Self-inflicted burns in a National Swedish Burn Centre: an overview.

In the Western world, self-inflicted burns are often associated with mental health disorders, and the management, particularly the pain treatment, can often be complicated by the psycho-social background of the patients. The aim was to describe a group of patients with self-inflicted burns by analysing their in-hospital mortality and the use of sedation during procedures. All patients with self-inflicted burns admitted to the Linköping Burn Centre during 2000-2017 were included. The control group consisted of adults (≥17 years) with accidental burns, admitted during the same period. Multivariable logistic and linear regression was used for analysis. Three percent of all patients (47/1601) had self-inflicted burns: most of them were men (60%, 28/47), none was younger than 17 years, and flame was the major cause of injury. Self-inflicted burn patients were younger and had larger burns: mean age (SD) was 42 (16) and 49 (20) years, respectively; mean TBSA (SD) was 29% (26) and 14% (17), respectively. The crude rate of procedures done under sedation was higher (mean (SD) 0.37 (0.23) compared with 0.24 (0.25)) as was crude in-hospital mortality (8/47, 17% compared with 72/1018, 7%). Multivariable analyses showed no difference in the use of sedation for procedures or in-hospital mortality after adjustment for TBSA%, full thickness burns, age and sex. Age and TBSA% were associated with in-hospital mortality, whereas the intentionality of the burn was not. TBSA% and female sex were associated with increased use of sedation for wound care procedures, whereas self-inflicted burns were not.

Dans les pays développés, les brûlures volontaires entrent souvent dans le cadre d'une pathologie psychiatrique, qui peut interférer avec leur traitement, en particulier l'analgésie. Le but de cete étude était de décrire un groupe de patients brûlés par tentative de suicide hospitalisés dans le CTB de Linköping entre 2000 et 2017, en analysant la mortalité et le recours à la sédation, comparativement à une population d'adultes (≥ 17 ans) hospitalisés durant la même période après une brûlure accidentelle. Nous avons utilisé une analyse logistique linéaire multivariée. Les suicidants représentaient 3% des patients (47/1 601), 60% (28/47) étaient des hommes, aucun n'avait moins de 17 ans et une flamme était le plus souvent cause de la brûlure. Les suicidants étaient plus jeunes (42 +/- 16 VS 49 +/- 20 ans) et plus extensivement brûlés (29 +/- 26% VS 14 +/- 17%). Les pansement étaient plus fréquemment réalisés sous sédation (37 +/- 23% des cas VS 24 +/- 25%) et la mortalité était plus élevée (17% - 8/47 VS 7% - 72/1018). En analyse multivariée et après ajustement sur la surface brûlée, on ne trouve pas de différence de mortalité, de recours à la sédation, de brûlures profondes, d'âge ni de sexe, la surface brûlée et l'âge étant associées à la mortalité mais pas le caractère intentionnel. Les femmes avaient plus souvent besoin de sédation que les hommes, le recours à la sédation tant en outre associé à la surface brûlée mais pas l'inentionnalité.

Development and application of degradation kinetics of thin layer chromatographic densitometry and conductometric methods for butoconazole nitrate determination.

Two simple methods were developed for determination of butoconazole nitrate (BN). The first developed method was stability-indicating HPTLC-densitometric method (method A) which is based on the quantitative densitometric separation of butoconazole nitrate (BN) from its degradation products on silica gel 60 F254 and measurement of the bands at 290nm. The developed stability study of BN was performed under different stress conditions including oxidative, hydrolytic, thermal and photolytic. Degradation was observed under acidic hydrolytic and oxidative conditions. Moreover, the HPTLC method was used to study the kinetics of BN acid degradation, determining as first order kinetics. The degradation rate constant of BN was found to be 0.076 hr-1 and t 1/2 value was determined at 9.12 hr in acidic medium. The second method (Method B) was conductometric method which is based on the reaction of BN with phosphotungstic acid (PTA) to form an ion associate in 50% methanol-water system. Validation of the proposed methods was carried out. All proposed methods were successfully applied for the commercial dosage form of BN. Statistical analysis of the results has been carried out revealing high accuracy and good precision.

Immunohistochemical hENT1 expression as a prognostic biomarker in patients with resected pancreatic ductal adenocarcinoma undergoing adjuvant gemcitabine-based chemotherapy.

BACKGROUND: Human equilibrative nucleoside transporters (hENTs) are transmembranous proteins that facilitate the uptake of nucleosides and nucleoside analogues, such as gemcitabine, into the cell. The abundance of hENT1 transporters in resected pancreatic ductal adenocarcinoma (PDAC) might make hENT1 a potential biomarker of response to adjuvant chemotherapy. The aim of this study was to see whether hENT1 expression, as determined by immunohistochemistry, was a suitable predictive marker for subsequent treatment with gemcitabine-based adjuvant chemotherapy. METHODS: A systematic review was performed, searching databases from January 1997 to January 2016. Articles pertaining to hENT1 immunohistochemical analysis in resected PDAC specimens from patients who subsequently underwent adjuvant gemcitabine-based chemotherapy were identified. Eligible studies were required to contain survival data, reporting specifically overall survival (OS) and disease-free survival (DFS) with associated hazard ratios (HRs) stratified by hENT1 status. RESULTS: Of 42 articles reviewed, eight were suitable for review, with seven selected for quantitative meta-analysis. The total number of patients included in the meta-analysis was 770 (405 hENT1-negative, 365 hENT1-positive). Immunohistochemically detected hENT1 expression was significantly associated with both prolonged DFS (HR 0·58, 95 per cent c.i. 0·42 to 0·79) and OS (HR 0·52, 0·38 to 0·72) in patients receiving adjuvant gemcitabine but not those having fluoropyrimidine-based adjuvant therapy. CONCLUSION: Expression of hENT1 is a suitable prognostic biomarker in patients undergoing adjuvant gemcitabine-based chemotherapy.

Role of staging laparoscopy in the stratification of patients with perihilar cholangiocarcinoma.

BACKGROUND: Cholangiocarcinoma is a rare cancer with a poor prognosis. Radical surgical resection is the only option for curative treatment. Optimal determination of resectability is required so that patients can be stratified into operative or chemotherapeutic treatment cohorts in an accurate and time-efficient manner. Staging laparoscopy is utilized to determine the presence of radiologically occult disease that would preclude further surgical treatment. The aim of this study was to analyse the utility of staging laparoscopy in a contemporary cohort of patients with perihilar cholangiocarcinoma. METHODS: Patients diagnosed with potentially resectable perihilar cholangiocarcinoma between January 2010 and April 2015 were analysed retrospectively from a prospective database linked to UK Hospital Episode Statistics data. Patients with distal cholangiocarcinoma and gallbladder cancer were excluded from analysis. RESULTS: A total of 431 patients with perihilar cholangiocarcinoma were referred for assessment of potential resection at a supraregional referral centre. Some 116 patients with potentially resectable disease subsequently underwent surgical assessment. The cohort demonstrated an all-cause yield of staging laparoscopy for unresectable disease of 27·2 per cent (31 of 114). The sensitivity for detection of peritoneal disease was 71 per cent (15 of 21; P < 0·001). The accuracy for all-cause non-resection for staging laparoscopy was 66 per cent (31 of 47) with a positive predictive value of progress to resection of 81 per cent (69 of 85). Neither the Bismuth-Corlette nor the Memorial Sloan Kettering Cancer Center preoperative scoring system was contingent with cause of unresectability at staging laparoscopy (P = 0·462 and P = 0·280 respectively). CONCLUSION: In the present cohort, staging laparoscopy proved useful in determining the presence of radiologically occult metastatic disease in perihilar cholangiocarcinoma.

Academic requirements for Certificate of Completion of Training in surgical training: Consensus recommendations from the Association of Surgeons in Training/National Research Collaborative Consensus Group.

BACKGROUND: Surgical trainees are expected to demonstrate academic achievement in order to obtain their certificate of completion of training (CCT). These standards are set by the Joint Committee on Surgical Training (JCST) and specialty advisory committees (SAC). The standards are not equivalent across all surgical specialties and recognise different achievements as evidence. They do not recognise changes in models of research and focus on outcomes rather than process. The Association of Surgeons in Training (ASiT) and National Research Collaborative (NRC) set out to develop progressive, consistent and flexible evidence set for academic requirements at CCT. METHODS: A modified-Delphi approach was used. An expert group consisting of representatives from the ASiT and the NRC undertook iterative review of a document proposing changes to requirements. This was circulated amongst wider stakeholders. After ten iterations, an open meeting was held to discuss these proposals. Voting on statements was performed using a 5-point Likert Scale. Each statement was voted on twice, with ≥80% of votes in agreement meaning the statement was approved. The results of this vote were used to propose core and optional academic requirements for CCT. RESULTS: Online discussion concluded after ten rounds. At the consensus meeting, statements were voted on by 25 delegates from across surgical specialties and training-grades. The group strongly favoured acquisition of 'Good Clinical Practice' training and research methodology training as CCT requirements. The group agreed that higher degrees, publications in any author position (including collaborative authorship), recruiting patients to a study or multicentre audit and presentation at a national or international meeting could be used as evidence for the purpose of CCT. The group agreed on two essential 'core' requirements (GCP and methodology training) and two of a menu of four 'additional' requirements (publication with any authorship position, presentation, recruitment of patients to a multicentre study and completion of a higher degree), which should be completed in order to attain CCT. CONCLUSION: This approach has engaged stakeholders to produce a progressive set of academic requirements for CCT, which are applicable across surgical specialties. Flexibility in requirements whilst retaining a high standard of evidence is desirable.

Scald management protocols - outcome differences in two different time periods using different treatment strategies.

Over the years the treatment of scalds in our centre has changed, moving more towards the use of biological dressings (xenografts). Management of scalds with mid dermal or deep dermal injuries differs among centers using different types of dressings, and recently biological membrane dressings were recommended for this type of injury. Here we describe differences in treatment outcome in different periods of time. All patients with scalds who presented to the Linkoping Burn Centre during two periods, early (1997-98) and later (2010-12) were included. Data were collected in the unit database and analyzed retrospectively. A lower proportion of autograft operations was found in the later period, falling from 32% to 19%. Hospital stay was shorter in the later period (3.5 days shorter, p=0.01) and adjusted duration of hospital stay/TBSA% was shorter (1.2 to 0.7, p=0.07). The two study groups were similar in most of the studied variables: we could not report any significant differences regarding outcome except for unadjusted duration of hospital stay. Further studies are required to investigate functional and aesthetic outcome differences between the treatment modalities.

Le traitement des brûlures par liquides chauds a changé avec le temps, évoluant de plus en plus vers l'usage des pansements biologiques (xénogreffes). La prise en charge de ce type de brûlures (de profondeur moyenne ou profonde) diffère suivant les centres qui utilisent différents types de pansements et plus récemment, les membranes biologiques ont été recommandées pour ce type de traumatisme. Dans cette étude, nous décrivons les résultats thérapeutiques obtenus au cours de différentes périodes. Tous les patients avec des brûlures par liquides chauds admis au Centre de brûlés Linkoping pendant deux périodes d'abord de 1997-1998 et plus tard de 2010 à 2012 ont été inclus. Les résultats de notre banque de données ont été recueillis et analysés de façon rétrospective. Une proportion basse de greffes cutanées a été retrouvée dans la dernière période passant de 32% à 19%. Le séjour à l'hôpital a été également raccourci dans cette période (3,5 jours en moins, p= 0,01) et la durée d'hospitalisation en rapport avec l'étendue a diminué (1,2 à 0,7, p=0,07). Les résultats dans les deux groupes étaient semblables dans la plupart des variables étudiées: nous ne trouvons pas de différence significative sur le plan des résultats, excepté pour la durée d'hospitalisation. De nouvelles études sont nécessaires pour évaluer les divers résultats fonctionnels et esthétiques en fonction des modalités thérapeutiques.

Temporary coverage of burns with a xenograft and sequential excision, compared with total early excision and autograft.

During the 80s and 90s, early and total excision of full thickness burns followed by immediate autograft was the most common treatment, with repeated excision and grafting, mostly for failed grafts. It was hypothesized, therefore, that delayed coverage with an autograft preceded by a temporary xenograft after early and sequential smaller excisions would lead to a better wound bed with fewer failed grafts, a smaller donor site, and possibly also a shorter duration of stay in hospital. We carried out a case control study with retrospective analysis from our National Burn Centre registry for the period 1997-2011. Patients who had been managed with early total excision and autograft were compared with those who had had sequential smaller excisions covered with temporary xenografts until the burn was ready for the final autograft. The sequential excision and xenograft group (n=42) required one-third fewer autografts than patients in the total excision and autograft group (n=45), who needed more than one operation (p<0.001). We could not detect any differences in duration of stay in hospital / total body surface area burned% (duration of stay/TBSA%) (2.0 and 1.8) (p=0.83). The two groups showed no major differences in terms of adjusted duration of stay, but our findings suggest that doing early, smaller, sequential excisions using a xenograft for temporary cover can result in shorter operating times, saving us the trouble of making big excisions. However, costs tended to be higher when the burns were > 25% TBSA.

Pendant ces dernières décades, l'excision précoce et totale des brûlures profondes, suivie immédiatement d'autogreffe a constitué le traitement le plus habituel avec souvent, en cas d'échec, des excisions répétées et de nouvelles greffes. Nous avons pensé, cependant, que la couverture par autogreffe retardée, précédée par une couverture temporaire par xénogreffe après des excisions itératives et moins larges permettait d'obtenir un meilleur lit receveur avec moins d'échecs, des sites donneurs plus petits et une durée d'hospitalisation moindre. Nous avons ainsi mené une étude analytique rétrospective dans notre Centre National de Brûlés pendant la période 1997-2011. Les patients qui avaient été traités par une excision précoce totale suivie d'autogreffe ont été comparés à ceux qui avaient eu des petites excisions séquentielles, couvertes de façon temporaire par des xénogreffes jusqu'à ce que la brûlure soit prête pour une autogreffe finale. Le groupe excision séquentielle et xénogreffe (n=42) a nécessité un tiers de moins d'autogreffes que les patients qui avaient une excision totale suivie d'autogreffe (n=45) et plus d'une seule opération (p<0001). Nous n'avons pas remarqué de différence dans la durée d'hospitalisation en fonction de l'étendue de la surface brûlée (durée du séjour TBSA%) (2,0 et 1,8) (p=0,83). Les deux groupes n'ont pas montré de différence majeure en terme de durée d'hospitalisation, mais l'excision précoce, limitée et séquentielle avec une xénogreffe temporaire, permet de réduire le temps opératoire et évite les excisions trop généreuses. Cependant les coûts ont tendance à être plus élevés avec les brûlures de 25% ou plus de TBSA.

The feasibility of spinal anesthesia with sedation for laparoscopic general abdominal procedures in moderate risk patients.

BACKGROUND: One of the major advantages of laparoscopic surgery is minimizing postoperative morbidity. The previous limitations to the use of spinal anesthesia in laparoscopic surgery were the limited work space, high failure rate, more intra-operative morbidity and significant arterial blood gas alterations. However, the addition of a small-dose Ketamine infusion to propofol might provide a suitable sedative combination to be used with high spinal anesthesia, producing titerable sedation, increased hemodynamic stability, and minimal respiratory depression. PATIENTS AND METHODS: At KFSH & RC Hospital, after Ethical Committee approval and informed written consent, 18 ASA III patients scheduled for various laparoscopic abdominal procedures were enrolled. Exclusion criteria consisted of ejection fraction below 45% and or peak expiratory flow rate and forced vital capacity of less than 65% of predicted values. Following oral premedication with midazolam 7.5-10 mg 30 min preoperatively, spinal anesthesia was conducted by bupivicaine 0.75% 3-3.5 ml at L3-4, in the lateral position to reach a sensory level at T4. Sedation was started by intravenous injection of 0.4 mg/kg propofol and 0.1 mg/kg ketamine prior to spinal anesthesia. This was followed by infusion of 1.0-1.5 mg/kg/h and 0.3-1.0 mg/kg/h. of the same drugs respectively. The sedation requirements were adjusted to keep the patient sleepy with conservation of airway reflexes at level 3 on a 5 point sedation score. Heart rate, respiratory rate and SpO2 were monitored, together with direct arterial blood pressure monitoring and arterial blood gas analysis through arterial cannulation. Postoperative first time call for analgesia, total morphine consumption during the first hour and incidence of complications were recorded. Twenty Four hours later, surgeons' and patients' satisfaction were obtained and recorded. RESULTS: Heart rate and mean arterial blood pressure were significantly decreased after spinal anesthesia and intra-peritoneal insufflations of CO2, with significant increase in arterial carbon dioxide tension accompanied by increase in the respiratory rate. The increase in respiratory rate led to gradual decrease of CO2 level down to near the pre-operative PaCO2 values. However, there was insignificant decrease in oxygen saturation throughout the intra-operative time. Postoperatively there were excellent surgeon and patient's satisfaction. Only one patient regained sensation before completion of surgery and sedation was deepened to level 5 sedation score. The mean surgical time was 98.5 +/- 21.4 min while the mean anesthesia time was 117.7 +/- 20.1 min. First mean time call for analgesia was 50 +/- 8 min. 7/18 patients required single dose of morphine of 4 mg during the 1st hour postoperatively. CONCLUSIONS: The addition of a sedative combination of ketamine and propofol to spinal anesthesia was found to be safe and efficient from both the anesthetic and surgical point of view, especially for sick patients with intermediate clinical predictors.

The digi-neocognitron: a digital neocognitron neural network model for VLSI.

One of the most complicated ANN models, the neocognitron (NC), is adapted to an efficient all-digital implementation for VLSI. The new model, the digi-neocognitron (DNC), has the same pattern recognition performance as the NC. The DNC model is derived from the NC model by a combination of preprocessing approximation and the definition of new model functions, e.g., multiplication and division are eliminated by conversion of factors to powers of 2, requiring only shift operations. The NC model is reviewed, the DNC model is presented, a methodology to convert NC models to DNC models is discussed, and the performances of the two models are compared on a character recognition example. The DNC model has substantial advantages over the NC model for VLSI implementation. The area-delay product is improved by two to three orders of magnitude, and I/O and memory requirements are reduced by representation of weights with 3 bits or less and neuron outputs with 4 bits or 7 bits.

Distinct biochemical features of interferon gamma receptors on human T lymphocytes.

Recombinant human gamma interferon (IFN gamma) was used to study IFN gamma receptors (IFN gamma-R) on human CD4+ and CD8+ peripheral blood T lymphocytes. When cell-bound 125I-IFN gamma was cross-linked by disuccinimidyl suberate, the receptor-ligand complex migrated under nonreducing conditions as major bands of 155 kD and 90 kD and a minor band of 65-70 kD. Under reducing conditions, only the 90 and 65 kD complexes were found; the 155 kD band was not seen. In contrast, complexes from WISH and Raji human lines exhibited a single band of a 125 kD under both reducing and nonreducing conditions. The molecular pattern of the receptor ligand complex on WISH cells was not altered when these cells were mixed with T lymphocytes during the extraction procedure. The results suggest that the IFN gamma receptor on T lymphocytes differs from those previously described.

Prostaglandin E2 selectively increases interferon gamma receptor expression on human CD8+ lymphocytes.

We previously reported that prostaglandin E2 (PGE2) at a physiologic concentration (10(-8) M) and interferon gamma (IFN gamma), acting sequentially, were required for the differentiation of suppressor cells in mitogen-stimulated cultures. The present study was designed to test whether PGE2 might mediate IFN gamma-dependent effects on CD8+ cells by altering the number and/or affinity of their IFN gamma receptors. CD8+ and CD4+ cells when cultured for 18 h expressed comparable numbers of IFN gamma receptors of a single high affinity. Incubation with 10(-8) M PGE2 for 18 h, however, increased the number of IFN gamma receptors on CD8+ cells without affecting the binding affinity. Similar effects were not observed with CD4+ cells, nor when CD8+ cells were cultured in 10(-8) M PGD2. Concentrations of PGE2, which were ineffective in the induction of IFN gamma-dependent suppressor cell differentiation, also did not affect IFN gamma receptor expression on CD8+ cells. This observation of a specific stimulatory effect of PGE2 on the display of IFN gamma receptors of CD8+ cells suggests a novel mechanism for eicosanoid function through tissue-specific regulation of hormone receptors.

Sequential effects of prostaglandins and interferon-gamma on differentiation of CD8+ suppressor cells.

We have previously demonstrated that differentiation of CD8+ Tp44- suppressor cells in pokeweed mitogen (PWM)-stimulated cultures requires soluble factors elaborated by CD4+ cells and monocytes, and that the monocyte signal for such differentiation can be replaced by prostaglandin E2 (PGE2). In this study, we explored the ability of interleukin 2 (IL 2) and interferon-gamma (IFN-gamma) to replace the CD4+ signal. When IL 2 or IFN-gamma was used at concentrations equivalent to those present in supernatants of PWM-pulsed cultures of CD4+ cells, no effect on differentiation of CD8+ cells was observed. However, a potent suppressor inducing activity was detected when IFN-gamma, but not IL 2, was mixed with supernatants derived from cultures of PWM-pulsed purified monocytes (M phi sup) or with 10(-8) M PGE2. Differentiated CD8+ suppressor cells (Ts) inhibited both PWM-stimulated proliferative response of CD4+ cells and immunoglobulin production by B cells. The signals mediated by the M phi sup or PGE2 and IFN-gamma were shown to act sequentially. That is, M phi sup or PGE2 was required initially, followed by an IFN-gamma-dependent differentiative step. These studies thus suggest a cascade of cellular interactions involving monocytes, CD4+ cells, and CD8+ Ts precursors that are required for the differentiation of CD8+ suppressor effector cells.

T suppressor cell growth factor and anti-CD3 antibodies stimulate reciprocal subsets of T lymphocytes.

Because of the central role of IL-2 in clonal expansion of T cells, we have postulated that lymphocyte subpopulations with opposing regulatory functions might be independently regulated by differential requirements for expression of cell-surface IL-2-R. Purified CD4+ and CD8+ cells proliferated in an IL-2-dependent manner to crosslinked anti-T cell receptor antibodies (anti-CD3-Seph). Similarly, both CD4+ and CD8+ cells became IL-2 responsive after incubation in T suppressor cell growth factor (TsGF), a newly described approximately 8,000 Mr product of activated CD4+ cells. In support of our hypothesis, however, we observed that subpopulations of CD4+ and CD8+ cells, possessing distinct cell-surface antigens, showed differential responses to these stimuli. Those cells of suppressor-inducer or suppressor-effector phenotype failed to proliferate when cultured in anti-CD3-Seph plus IL-2, but did proliferate in an IL-2-dependent manner to TsGF. Furthermore, the suppressor-effector population was unresponsive to TsGF plus IL-2 when cocultured in anti-CD3-Seph, suggesting that functionally induced Ts may be refractory to growth stimuli. Conversely, cells with helper-inducer or cytolytic phenotype proliferated when incubated in anti-CD3-Seph and IL-2, while remaining essentially unresponsive to TsGF and IL-2. The results could not be explained by differences in the level of CD3 expression by the T cell subsets. Thus, cells within the helper and suppressor lineages appear to have distinct and reciprocal patterns for the induction of IL-2 responsiveness.

Human suppressor T cells: induction, differentiation, and regulatory functions.

T-cell-mediated suppression of human immune responses involves a complex interaction between distinct lymphocyte subsets with suppressor-inducer and suppressor-effector functions. Recent studies with subset-specific monoclonal antibodies have defined a characteristic phenotype of suppressor-inducer cells (CD4+ Leu8+ 2H4+ 4B4-) that can be distinguished from that of helper cells for antibody synthesis (CD4+ Leu8- 2H4- 4B4+). Similarly, suppressor-effector cells (CD8+CD11+Tp44-) can typically be defined as a subset separable from cytotoxic T cells (CD8+CD11-Tp44+). Both antigen-specific and nonspecific interactions are important in suppressor T-cell activation and function. Soluble signals required for differentiation of CD8+ suppressor cells include an indomethacin-sensitive monocyte product and interferon gamma. In contrast, proliferation of the CD8+ suppressor cell subset depends on stimulation first by a product of CD4+Leu8+ cells, T suppressor cell growth factor, and second by interleukin 2. Although the molecular basis of antigen-specific interactions between CD4+ and CD8+ cells in suppressor cell generation has not been defined, it may involve both conventional, presumably MHC-restricted, interactions between antigen and antigen receptors, as well as anti-idiotypic interactions of suppressor-effectors with determinants on suppressor-inducer receptors. Progress in elucidating requirements for activation, growth, and differentiation of suppressor cells should facilitate long-term culture of such cells and lead to clearer understanding of mechanisms of suppressor-cell mediated immunoregulation.